This invention relates to heating devices, particularly heat reclamation devices that are adapted to be attached to ovens, ranges or similar cooking appliances so as to reclaim waste heat from the exhaust thereof in order to heat buildings or vehicles in which the cooking appliance is located, while requiring minimal space and being relatively maintenance free.
Ovens, ranges and similar cooking appliances generate waste heat in their exhaust that is ordinarily lost in venting the exhaust to the atmosphere. It is often desirable to reclaim the waste heat from that exhaust in order to heat, for example, the interior spaces of the building or vehicle in which the cooking appliance is located. It is also desirable to reclaim that heat using a device that consumes a minimal amount of space, is lightweight, is relatively maintenance free, is thermally efficient, and includes a simple means by which the extraction of heat may be selectively turned on or off. In addition, it is desirable to reclaim the heat using a device that vents dangerous gases and moisture out of the appliance into the atmosphere, rather than into living spaces, and that provides sufficient draft as to prevent backdraft of the gases and moisture into the cooking appliance.
The above-identified features are particularly desirable when reclaiming heat in small manufactured homes, campers, motor homes, trailers and other structures where interior space generally is limited and cooking appliances frequently use propane, a fuel that produces exhaust containing moisture and dangerous gases.
Heating devices that reclaim waste heat from the exhaust of various heat sources for use in heating living spaces are known, and take a variety of forms, each with significant limitations. One conventional form includes an enclosure seated on and covering the entire cooking surface of a stove. The enclosed air is heated both by the stove's radiant heat and by the waste heat contained in the stove's exhaust. Examples of this form are described in Rogant U.S. Pat. No. 2,553,278 and Hilby U.S. Pat. No. 413,367.
This form of heating device is subject to significant limitations, including that the simultaneous use of the stove for heating and for cooking is precluded because the enclosure must be either seated to heat o removed to cook. This form also tends to consume a large amount of space. Accordingly, this form is not well adapted for use in small manufactured homes, campers, motor homes, trailers and other such structures.
A second conventional form reclaims waste heat from the exhaust of a cooking surface by collecting the exhaust using a hood fixed in position above and away from the cooking surface. This form is particularly adapted for use in restaurants. An example of this form is described in Huggins U.S. Pat. No. 4,171,722 ("Huggins").
This second form of heating device, as shown by Huggins, is also subject to significant limitations. For example, Huggins is complex in design, requiring a hood, conduits, blowers, filters, heat exchanger elements, dampers, and an electric motor. With its complexity, Huggins' heating device tends to be expensive and to require a relatively high amount of maintenance. Moreover, Huggins' heating device consumes a large amount of space, and it is to be installed largely on the exterior of the structure in communication with the cooling surface and the heated space by means of a network of conduits. Accordingly, this form also is not well adapted for use in small manufactured homes, campers, motor homes, trailers and other such structures.
A third conventional form of heating device reclaims waste heat from the flue gases of heating stoves and furnaces. This form generally is used to supplement the heat generated by heating stoves and furnaces, and is available in a large number of variations having various features. In one variation, this form is positioned above and behind the stove and consumes a smaller amount of space than the aforementioned forms, in particular, by having a somewhat flat geometry. An example of this form is described in Johnson U.S. Pat. No. 4,206,742 ("Johnson") wherein flue gases pass though a set of vertical tubes having outside surfaces that transfer heat to air directed thereover by a blower.
This third form of heating device is also subject to significant limitations, including that this form tends to consume more than the desired minimal amount of space. Although Johnson is somewhat flat in geometry, it must be deep enough to accommodate a large number of tubes disposed in spaced, offset rows so as to provide efficient heat exchange. Moreover, use of tubes increases maintenance because the tubes' relatively narrow internal diameter tends to cause depositing that must be removed regularly when the heat source's exhaust contains particulates. Indeed, Johnson provides access to the tubes in order to facilitate that maintenance. While wider diameter tubes may be used to lessen maintenance, such wider tubes tend to increase space consumption by increasing the depth of the apparatus and tend to reduce heat reclamation efficiency. Accordingly, this form also is not well adapted for use in small manufactured homes, campers, motor homes, trailers and other such structures.
Because known conventional heating devices that reclaim heat have inherent shortcomings when used in small manufactured homes, campers, motor homes, trailers and other such structures, a need exists for an improved heating device that reclaims waste heat, particularly for use in such buildings and vehicles.